When grandma is flying in for a special occasion, you'll find a spot in the airport's short-term parking garage, go into the terminal and wait where you'll be sure to see her when she exits the secure area.

But if it's "just" a friend coming in for the weekend or a spouse coming home from a quick business trip, these days you're likely to wait in your car in the cellphone lot, have your friend or family member call you when they've landed and then drive over and make a quick pick-up at the curb.

Cellphone lots offering free, short-term parking near airports are now available at most large, medium and many small airports. But just ten years ago, none of these lots even existed. Their presence at airports is the result of two post-9/11 trends we now take for granted: heightened concerns about security outside the terminals and the growing number of people using cellphones.

After 9/11, motorists waiting for passengers to arrive were no longer allowed to clog up roadways outside airport terminals by idling for a long time at the curb, or leaving a car parked outside baggage claim and running inside to greet a passenger. It's hard to believe now, but in the "old days," many airports would let you do that.

To cut down on congestion caused by drivers who instead began circling terminal lanes over and over, in 2004 airports such as Los Angeles International and Seattle-Tacoma International came up with the idea of directing drivers to free, off-site parking lots where they could wait for an arriving passenger with a cellphone to call for a pick-up. At least a dozen airports had cellphone waiting lots by the end of 2004 and today it's rare – and irritating – to find an airport without one.

"Security concerns and technology have definitely driven the rise of this airport amenity" said Debbie McElroy, spokesperson for ACI-NA, the organization that represents most North American airports.

But so has economics. In the past, many airports gave drivers a grace period in the parking garage, anywhere from 15 to 60 minutes, to allow them to go into the terminal and meet a passenger. But most of these free parking sessions have been eliminated as airports try to maximize revenue generated from their parking garages. "Airports still want to provide good service to their communities," said McElroy, "so when they cut free parking they'll often add a cellphone waiting lot nearby."

And while many cellphone lots are put on property an airport wasn't using for anything else, the lots do have costs. "You have to establish them, maintain them and make sure you have periodic security checks," McElroy said. "And in some airports, the lots are on land that could otherwise be put to use generating some sort of revenue."

But cellphone lots are now so popular that many airports are now expanding theirs and adding amenities for waiting drivers such as free Wi-Fi, vending machines, restrooms (portable and permanent) and electronic reader boards displaying up-to-date flight arrival information.

At Fort Lauderdale Hollywood International Airport, community outreach coordinator Allan Siegel says the airport offers a flight-status screen as well as emergency services for vehicles with a flat tire or dead battery. And at the Austin-Bergstrom International Airport, there are flight information display monitors, restrooms and regular food truck service offering Mexican food, Panini sandwiches, salads, appetizers and drinks.

The Tampa airport has been experimenting with having a different food truck on-site each day.(Photo: Courtesy Tampa International Airport)

Tampa International Airport has vending machines, restrooms, real-time flight information, free Wi-Fi, and electric vehicle charging stations in its cellphone lot and, before the holidays it began a 30-day experiment with having food trucks on-site as well, a different one each day.

The experiment has been such a success that the trial period has been extended. The airport is even posting the food truck schedule on its Facebook page.

"Other airports are watching Tampa to see how successful they are in doing this," said McElroy, "And I think there's probably room for other airports to contract with vendors to offer more services and amenities at their cellphone lots as well."

But what kinds of services and amenities might be added?

Tim O'Krongley, assistant aviation director for the San Antonio Airport System, said there's been some discussion about adding food truck service at San Antonio International Airport. And when Seattle-Tacoma International Airport opens a new, larger permanent cellphone lot next spring, free Wi-Fi and some food options may be added as well.

But here are some other options that might make cellphone lots even more enticing: drive-through espresso stands, exercise stations, playgrounds, fresh flower stands and coin-operated car washes and vacuums to encourage drivers to clean up their cars before going in for the pick-up.

Readers: What amenities would you like to see at an airport cellphone waiting lot? Please leave your ideas in the comments section.